So checking out the differences between the two tv's I noticed these as the following differences.

G series has over S series:

Normal, Zoom, Full, Just, H-fill for TV/AV modes
4:3, Full for PC mode

S series only has Normal, Zoom, Full, Just, H-fill

G12 Progressive 1080p HD NeoPDP (Plasma Display Panel)

S series says just G12 Progressive 1080p Plasma Display Panel

x.v colour, s series doesn't have this

3d color management and sub pixel control, s series lacks these also.

Mini D-sub 15-pin x 1 (rear), s series lacks this.

Now how much of a visual difference do this options on the G series make over the S, and then is it really worth buying the G and not just going up to the V series instead?

If you're in the US, the G10 also has THX (as does the V10). In many European countries, however, you have to go to the V10 for THX.